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HD Ratio for IPv4

HD Ratio for IPv4. LACNIC VI Mar 29 - Apr 1, 2004 Montevideo, Uruguay. Current status. APNIC Similar presentation at APNIC 16 Received positive feedback for the concept ARIN Proposal currently discussing on mailing list LACNIC Information and consideration RIPE NCC

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HD Ratio for IPv4

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  1. HD Ratio for IPv4 LACNIC VIMar 29 - Apr 1, 2004 Montevideo, Uruguay

  2. Current status • APNIC • Similar presentation at APNIC 16 • Received positive feedback for the concept • ARIN • Proposal currently discussing on mailing list • LACNIC • Information and consideration • RIPE NCC • Information presentation in coming meeting

  3. Background • Host Density (HD) ratio • Measures utilisation in hierarchically managed address space (see RFC3194 and RFC1715) • Note: calculation requires registration of individual site addresses (/48) • The HD-ratio has been adopted for IPv6 • LIR may receive more IPv6 space when HD=0.80 • An HD-ratio value corresponds to a percentage utilisation which decreases as the size of the address space grows

  4. /32 /16 10.9% 1.18% Background - IPv6 (HD = 0.80) • RFC3194 “The Host-Density Ratio for Address Assignment Efficiency”

  5. Problem Summary • IPv4 fixed utilisation requirement • Once 80% is sub-allocated or assigned, LIR can request additional block • Same requirement for all address blocks, regardless of size • No allowance for hierarchical management • Address management efficiency decreases for large address blocks • Imposes unreasonable management overhead on larger LIRs

  6. Proposal Summary • HD-based IPv4 utilisation requirement • Lower % utilisation requirement for larger blocks • To make allowance for hierarchical management • Variation of HD-Ratio proposed • Assignment Density (AD) Ratio • Proposed value • Utilisation requirement AD=0.966 • Calculated based on current 80% principle

  7. Proposed IPv4 utilisation (AD 0.966)

  8. Proposed IPv4 utilisation (AD 0.966)

  9. Justification

  10. ISP … Customers and Infrastructure Allocation Hierarchy - 1 RIR

  11. ISP “Internal” Hierarchy … Allocation Hierarchy - 2 RIR Customers and Infrastructure

  12. Assignment Density (AD) Ratio • Variation of HD ratio • Instead of measuring host addresses actually used, measures number of addresses assigned by LIR • For consistency with IPv4 policies, which do not track individual host address assignments • Propose to use AD Ratio as utilisation measure for IPv4 • Need to determine appropriate value

  13. Selecting an AD-Ratio value • Principles • Accept 80% as reasonable utilisation limit for single-level hierarchy • Accept corresponding lower utilisation limits for deeper hierarchies • 64% for 2-level hierarchy (80% x 80%) • 51.2% for 3-level hierarchy (80% ** 3) • Apply to ISP internal hierarchy • We assume likely useful depth of hierarchy according to size of address space • Select values which appear reasonable • Values are theoretical only

  14. ISP Internal Hierarchy* … Allocation Hierarchy RIR Customers and Infrastructure

  15. Selecting an AD-Ratio value • Likely depth of ISP addressing hierarchy • Common AD Ratio value • Most conservative: 0.966 • Lease conservative: 0.961

  16. IPv4 utilisation (AD = 0.966)

  17. Impact

  18. Impacts • Administrative • LIR needs to incorporate new method of calculating utilisation in procedures • LIR would need to register infrastructure assignments/sub-allocations • RIRs Secretariat update internal policies, procedures and documentation • Address space consumption • Initial impact • Ongoing impact

  19. Impact - Address Consumption • Initial impact • Maximum impact (address “wastage”) can be calculated as difference in utilisation expectation for all allocated address space • * Figure calculated from sample of 788 APNIC LIRs, according to actual address space holdings

  20. Impact - Address Consumption • Ongoing impact • Calculated by modeling the distribution of an additional /8 proportionally to all LIRs

  21. Implementation • RIR-LIR procedures • Replace 80% utilisation with 0.966 AD ratio • Assignment procedures • Calculations rely on assignment and sub-allocation registration information • Preferably including infrastructure

  22. Summary • Accept HD-Ratio based to measure utilisation requirement for hierarchical address management • Use AD-Ratio to apply for Ipv4 • Use 0.966 as AD-Ratio as a requirement • Benefit impacts larger ISPs • Improves address manageability • Address space consumption impact • Initial impact - up to 19% additional space required (maximum eventual impact) • Ongoing impact - up to 22% increase in consumption rate (maximum)

  23. Questions? Feedback?

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